Limitations of practical multiphoton decoherence-free states
Yong-Sheng Zhang, Chuan‐Feng Li, Yun‐Feng Huang, Guang‐Can Guo · Physical Review A · 2005
It is shown that the decoherence-free subspace (DFS) of practical multiphoton polarization cannot avoid exponential decoherence even in the same extra environment if the photons are frequency anticorrelated. The reason lies in the fact that the condition of collective decoherence is not satisfied in this case. As an example, the evolution of a biphoton decoherence-free state is given. A possible solution for a feasible multiphoton DFS state is also given.